Tunneling machine with center cutter and debris removing means

ABSTRACT

The invention is directed to a tunnel-driving machine designed to bore a tunnel and having, in addition to a large outer cutter wheel, a smaller central cutter wheel which is mounted near the hub of the outer cutter wheel and which enables the formation of soil plugs and dead cores to be avoided along the longitudinal axis of the cutting wheel, thus reducing the resistance of the machine to forward motion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention concerns a tunneling machine for boring a tunnel, with ashield that can be driven into the soil and in which a cutting wheel,powered and equipped with ripping tools, is arranged.

2. Description of the Invention

Tunneling of this type are known and feature a cutting wheel withseveral cutting arms, where the ripped soil proceeds through the spacesin the cutting arms into the tunneling machine and is then removed.Owing to the high forces which occur, the hub area of the cutting wheel,originating from which the cutting arms extend radially outward, is of amassive and stabile design. Therefore, soil ripped in the area of thelongitudinal axis of the cutting wheel needs to be moved in the radialdirection of the cutting wheel up to one of the spaces between thecutting arms of the cutting wheel. Besides, since in the center area ofthe cutting wheel the velocity of the ripping tools contained there islower than the velocity of the tools revolving on a larger radius, adead core results often in the axis area of the cutting wheel, withessentially a soil displacement taking place there, instead of an activesoil removal. The formation of a soil plug thus increases the forwardresistance of the tunneling machine, especially in cohesive soil, suchas loam and clay. To improve the escape of the soil in the dead core ofthe cutting wheel, slip layers have already been used. But these wearquickly, so that an initially slight forward resistance will in thecourse of time increase, due to the wear in the central area of thecutting wheel. The increased forward resistance with the prior tunnelingmachines reduces the rate of advance in tunneling and requires higherdriving capacities.

The problem underlying the invention is to provide a tunneling machinewhich is characterized by a low forward resistance.

SUMMARY OF THE INVENTION

The present invention provides a tunneling machine including a centercutter disposed in the hub area of the cutting wheel which is rotatablerelative to the cutting wheel and features as well ripping tools and acentral cutting wheel.

The central cutting wheel of the center cutter makes it possible to workin the dead core area independently of the ripping with the largercutting wheel. For that, the center cutter has for both directions ofrotation a drive mechanism which is separate from the cutting wheel. Tobe able to remove the soil in the dead core quickly and simply, thecenter cutter has at least one inlet opening for the soil to be ripped.The inlet opening empties into a crusher space fashioned as a conicalcrusher with several crushing bars which are arranged, for one, on thehub of the central cutting wheel and, for another, on the inside of thetapered plate of the conical crusher.

Flushing and suction lines are provided for removal of the soil enteringthe crusher space.

The central cutting wheel of the center cutter features preferably a rimcovering in the direction of advance an annular gap provided between thecenter cutter and the center cutter opening in the cutting wheel. In oneembodiment of the invention, the central cutting wheel of the centercutter is provided with several inlet openings, on the rims of whichthere are shearing blades or other ripping tools provided. Specifically,it is possible to equip the central cutting wheel with several rollerbits working in the direction of advance. Carbide tipping may beprovided along the rim of the central cutting wheel of the centercutter.

BRIEF DESCRIPTION OF THE DRAWINGS

Two embodiments of the invention will be more fully described hereafterwith the aid of the drawing, which shows in

FIG. 1, the front shield area of the tunneling machine according to theinvention, as a section with a cut-away partial view of the centercutter;

FIG. 2, a view of the tunneling machine according to FIG. 1, viewedagainst the direction of advance;

FIG. 3, an embodiment of the inventional tunneling machine modifiedrelative to FIG. 1, with a center cutter featuring roller bits, and

FIG. 4, a center cutter view corresponding to FIG. 3, scaled up somewhatas compared to FIGS. 2 and 3.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts in longitudinal section a shield 1 provided on the frontpart of a tunneling, or tunnel boring machine. The shield 1 possesses acylindrical shield shell 2 which on its front end pointing in thedirection of advance is provided with a shield cutting edge 3. With FIG.1 broken away toward the right, neither the tail of the shield 1 nor theremaining parts of the tunneling machine are shown in FIG. 1.

A center pipe 4 short in axial direction as compared to the shield shell2 extends coaxially to the shield shell 2. On its right-hand end in FIG.1, the center pipe 4 is fastened with the aid of a thrust wall 5 and, onits left-hand end in FIG. 1, with the aid of a plunge wall 6. Both thethrust wall 5 and the plunge wall 6 are ring-shaped, with the outsidediameter of the ring corresponding to the inside diameter of the shieldshell, the inside diameter of the ring to the outside diameter of thecenter pipe.

The plunge wall 6 is provided with a plunge wall opening 7 shown in FIG.1, bottom, which FIG. 2 illustrates in front elevation.

FIG. 2 presents the previously mentioned shield shell 2 and the plungewall 6, in front of which, in the direction of advance, an outer cuttingwheel 8 illustrated in FIGS. 1 and 2 is arranged.

The cutting wheel 8 has several cutting arms 9. Those of the outercutting wheel 8 are equipped each with several ripping tools 10 which inadvancing the tunneling machine remove the soil in the area of the face,with the soil, mixed with water, proceeding into the extraction chamber11 rearwardly defined by the plunge wall 6, and via the plunge wallopening 7 into the thrust chamber 12, whence the water-mixed soil ispumped with the aid of a centrifugal pump via a suction line 13 to aseparating plant which, for instance, is located above ground. To avoida clogging of the suction line 13, for instance the plunge wall opening7 is provided with a grate composed of several bars 14.

The cutting wheel 8 possesses in the area of its hub a receiving opening15 for accommodating a center cutter 16, fashioned for instance similarto a micromachine, with a central cutting wheel 17.

The outer cutting wheel 8, on its backside away from the ripping tools10, is provided with a mounting flange 18 which nonrotationally isjoined to a take-off flange 19. The latter is part of an outer cuttingwheel drive mechanism 20 capable of powering the outer cutting wheel 8both clockwise and counterclockwise. To that end there are severalhydraulic or electric motors 21 provided, which by way of reductiongears accommodated in reduction gear casings 22 are coupled with drivepinions 23, of which one is illustrated in FIG. 1.

The drive pinion 23 is installed in the main gearbox housing 24 of thetunneling machine and connected, via a pinion shaft 65, with thereduction gear of the drive motor 21. The main gearbox housing 24 has agearbox inner shell 25 fashioned as a short pipe section and extendingbetween a ring-shaped annular, front gearbox wall 26 and a rear gearboxwall 27.

As can be seen from FIG. 1, the main gearbox housing 24 is mounted onthe center pipe 4. A bearing 28 extends along the center pipe 4, withthe bearing outer race 29 rigidly secured to the main gearbox housing24, and the bearing inner race 30 to the take-off flange 19. The bearinginner race 30 has teeth 31 meshing with the teeth of the drive pinion23.

To prevent material from the extraction chamber 11 from proceeding intothe bearing 28, the take-off flange 19 is surrounded by a seal 32 whichis comprised of a race 33, a packing carrier 34, packing 35 and aclamping ring 36. Additionally, an inner seal 67 is provided along thetake-off flange 19 and the front gearbox housing wall 26.

Not illustrated in the drawing, a feed water line allows introducingwater or a water suspension into the thrust chamber 12, so that it isfilled constantly with liquid, for instance up to half of its height.The soil ripped with the aid of the outer cutting wheel 8 is removed viathe suction line 13 with the aid of the liquid supplied through thewater feed lines, as the cutting arms 9 are during the advance of thetunneling machine rotated clockwise or counterclockwise by means ofdrive motors 21.

To avoid a dead core formation in the hub area of the outer cuttingwheel 8, the previously mentioned central cutting wheel 17 is provided,which FIG. 1 depicts as a cut-away partial view and a sectional view,and FIG. 2 as a plan view opposite to the direction of advance.

The central cutting wheel 17 of the center cutter 16 has a crowned endface 37 provided with several inlet openings 38. Depicted in FIG. 2, theinlet openings 38 extend in radial direction up to a rim 39. Wide spokes40 are contained between the inlet openings 38.

As can be seen from FIG. 2, ripping tools 41, for instance shearingblades or round shank chisels, are provided along the inlet openings 38.

The central cutting wheel 17 has a hub 42 which extends into acone-shaped crusher space 43 and is nonrotationally connected with adrive disk 44.

Along the hub 42, several inner crushing bars 45 extend inside thecone-shaped crusher space 43, the latter being surrounded by a conicalplate 46 which is equipped with a plurality of outer crushing bars 47.Formed thereby is a stone crusher for the soil penetrating through theinlet openings 38. FIG. 2 as well depicts the inner crushing bars 45 andthe outer crushing bars 47.

Crushed in the conical crusher formed this way, the material leaves thecrusher space 43 via the annular gap 48, which communicates with aflushing or suction line 49 extending through the drive disk 44.

The crusher space 43 is surrounded by a feed water distributing space 50which in radial direction extends up to the housing shell 51 of thecenter cutter 16 and in axial direction up to a rear wall 52.

Provided in the rear wall 52 are several mouths of feed water lines 53,the feed water leaving the distributing space 50 through conduits 54, sothat material contained in the crusher space 43 can be removed via theannular gap 48 and the flushing and suction line 49. The feed or suctionline 49 can carry both liquid to the separating plant and feed waterfrom the separating plant.

Several drive motors 55 for powering the central cutting wheel 17 areprovided in the housing shell 51. As can be seen from FIG. 1, the drivedisk 44 comprises a rim 56 with which pinions 57 of the drive motors 55mesh. As can be seen further from FIG. 1, the drive disk 44 is installedby means of a bearing 58, with a front seal 59 and a rear seal 60ensuring the necessary tightness. The rim 39 protruding beyond theannular gap remaining in the receiving opening 15 has a sealing effectas well.

FIG. 3 shows the front part of a tunneling machine correspondingessentially to the structure shown in FIGS. 1 and 2, but with thecentral cutting wheel 17 provided with ripping tools other than shown inFIGS. 1 and 2. As follows from FIG. 3, the center cutter 16 shown thereis equipped with roller bits 70 mounted on a disk-shaped tool carrierplate 71.

The tool carrier plate 71 is depicted in FIG. 4 in plan view.Additionally, FIG. 4 shows a number of reinforcement ribs 72 and scraperbars 73. Components matching those in FIG. 1 and 2 are referenced thesame in FIGS. 3 and 4.

Also visible in FIG. 4 are a number of carbide tippings 74 along theperiphery of rim 39 of the central cutting wheel 17.

What is claimed is:
 1. A tunneling machine for boring a tunnel intosoil, comprising:a shield which is drivable into the said soil; arotatable cutting wheel disposed in said shield, said cutting wheelhaving a plurality of ripping tools and defining a hub area; a crusherspace; a center cutter disposed in said hub area, said center cutterrotatable relative to said cutting wheel, said center cutter including aplurality of ripping tools for loosening the said soil, and a centralcutting wheel, said central cutting wheel having at least one inletopening for permitting entry of the said loosened soil into said crusherspace; and a conduit connected to said crusher space to provide one offlushing action and suction action.
 2. Tunneling machine according toclaim 1, wherein said center cutter includes a drive mechanism separatefrom said rotatable cutting wheel for rotatably driving said centercutter in both directions of rotation.
 3. Tunneling machine according toclaim 1, wherein said central cutting wheel includes a hub and saidcrusher space comprises a conical crusher having a cone plate and aplurality of crushing bars, said crushing bars disposed on said hub andon an inside of said cone plate.
 4. Tunneling machine according to claim1, wherein the rotatable cutting wheel includes a receiving opening andsaid central cutting wheel includes a rim which in the direction ofadvance covers an annular gap provided for the center cutter and locatedbetween center cutter and said receiving opening.
 5. Tunneling machineaccording to claim 4, further comprising carbide tippings provided alongsaid rim.
 6. Tunneling machine according to claim 1, including at leastone shearing blade located at the edge of said one inlet opening. 7.Tunneling machine according to claim 1, wherein said central cuttingwheel includes a plurality of roller bits which work in the direction ofadvance.